According to the dand wiki, it gives you the dodge bonus against all attackers. I.E. you don't have to declare what opponent you get the bonus against.
That is regular Dodge if you use Pathfinder rules (which I recommend)
I'm playing a 20th level toon that has had 3.5 dodge for like 15 levels and I remember to actually declare it once about every 3 or 4 levels. Stupid feat!